An Introduction to Li-Fi

Advancements in Li-Fi Technology By Monenco Iran, July 2016

Advancements in Li-Fi Technology

Presented by Telecommunications Department,Monenco Iran



Presentation Organization

o Why a replacement for Radio?

o What is VLC?

o What about Li-Fi?

o History of Li-Fi

o How does it work?

o Li-Fi Hardware

o Lighting + Data

o Energy Harvesting + Data

o Li-Fi Networks

o Cellular Li-Fi

o Wireless HetNet and Li-Fi


Presentation Organization

o Applications of Li-Fi

o Li-Fi Technology key players

o Li-Fi Energy Efficiency

o Advantages and Limitations

o Comparison of Wi-Fi and Li-Fi

o Conclusion


Why a replacement for Radio?

• Radio Spectrum is really congested

• Some conducted researches found radio waves harmful to human health

• Radio spectrum offers less bandwidth compared to other portions of spectrum

• Using Radio is prohibited in certain areas

• Passing through walls makes it unsecure


What is VLC?

Optical Wireless Communication

(OWC)

Infrared (IR)

Visible Light Communication (VLC)

Ultraviolet Communication(UVC)


What is VLC?

Visible Light Communication

Any form of data communication via Visible Light


What is VLC?

Visible Light Communication


What is VLC?

The idea behind Visible Light Communication

• Radio Spectrum is BW limited and expensive

• IR is harmful to human eye

• UV, X-Ray and Gamma are harmful to human

body

• Visible spectrum (430 to 770 THz) is a good

choice and has the potential for high rate

data communication


What about Li-Fi?

Light Fidelity

• Li-Fi is the same as VLC but also defines networking features

• Like Wi-Fi, Li-Fi uses similar 802.11 protocols, but takes benefit of visible light as

the communication medium

• Li-Fi uses IEEE 802.15.7 standard for PHY and MAC layers


What about Li-Fi?

Key Features of Li-Fi

Mobile High Speed

Bidirectional Networked


History of Li-Fi

Alexander Graham Bell demonstrated the first VLC called Photophone in

1880

Bell's assistant transmitted a wireless voice telephone message over a 213m distance


History of Li-Fi

Modern Concept of Li-Fi was introduced by Professor Harald Haas at the

University of Edinburg in 2010

Haas demonstrated their concept of Li-Fi in a TED talk in 2011


History of Li-Fi

o A group of companies formed Li-Fi Consortium to promote high-speed optical

wireless systems in Oct. 2011

o Haas started PureLiFi in 2012, the first OEM company to commercialize Li-Fi

o In 2013 data rates of over 1.6 Gbit/s were demonstrated over a single color LED

o Uni-directional VLC was standardized under IEEE 802.15.7r1 specification in 2014

o In 2014 Sisoft tested data at speeds of up to 10 Gbit/s across a light spectrum

emitted by LED lamps


How does it work?

Main Components of a VLC System

Network Interface

Processing Board Light Source

Optical Medium Photodetector


How does it work?

A simple demo

White LED Photodetector


How does it work?

A simple demo


How does it work?


How does it work?

Data Modulation Light Source

PhotodetectorDemodulationData

Optical Path


How does it work?

o Data is used to modulate the intensity of LED light source

o Fast variations of current makes the optical output to vary at

extremely high speed

o The photodetector picks up the signal

o The receiver dongle then converts the tiny changes in amplitude

into a data stream


How does it work?

o Real-valued modulation schemes must be used to drive LEDs

Modulation Techniques

OOK PAM

PPMo These techniques suffer from inter-symbol interference (ISI) at high speeds


How does it work?

o At high data rate transfers, a more resilient technique, such as OFDM is desirable

o Conventional OFDM generates complex-valued bipolar signals

o Some modifications must be applied to convectional OFDM to be suitable for VLC

Modulation Techniques

OOFDM


How does it work?

Bidirectional and Multiple Access

• Users may see multiple Access Points

• Access Points may see multiple users


How does it work?

Mobility and Hand-over Support

• Users can move from one light source to

another

• Users may connect to the strongest light

source


Li-Fi Hardware

LED Technology Data Rates


Li-Fi Hardware

Receiver LiFi MIMO ASIC Transmitter LiFi MIMO ASIC


Lighting + Data

LEDs

+


Energy Harvesting + Data

+

Solar Cells


Li-Fi Networks

Fiber optics can be used to transfer

optical data streams between rooms


Cellular Li-Fi

Macrocell• Conventional cell towers covering 10s of km

Microcell• Covering about a km, used for temporary additional coverage

Picocell• Supporting 100 users and 100s of meters area, used to improve coverage in

offices and buildings

Femtocell• Supporting a few users and providing “5 bar” signal in a small area


Cellular Li-Fi

An optical Attocell network is an indoor small-cell cellular network based on VLC

Optical Attocell


Wireless HetNet and Li-Fi

Heterogeneous Network is used to maintain service when moving between cells


Applications of Li-Fi

Vehicles & Transportation



Indoor Positioning



Industrial RF Restricted Environments



Home/Office high speed optical downlink



In-Airplane Internet Access



Lecture/Seminar Halls



In Hospitals



Street lights as access points


Myths about Li-Fi

The lights flicker

Modulation is done at very high speed and is not sensible by human


Myths about Li-Fi

You cannot dim the lights

LEDs used for VLC are dimmable, however data rate decreases by dimming


Myths about Li-Fi

VLC is uni-directional

VLC can be used for transmission in either direction, however downlink-only implementations are simpler


Myths about Li-Fi

Downlink/Uplink Isolation

Wavelength Time Code Optical


Myths about Li-Fi

There will be interference from sunlight

Interferences from other sources can be simply eliminated using optical filters


Myths about Li-Fi

Lights need to be on so this is inefficient

In industrial, commercial and retail environments the lights are on when occupiedWatt/bit energy consumption for Li-Fi is comparable to radio


Myths about Li-Fi

You must have line-of-sight

It is preferable to have LOS, but Li-Fi can work in NLOS at lower speeds


Myths about Li-Fi

This is a disruptive technology

VLC is complementary to radio, like Wi-Fi and LTE


Myths about Li-Fi

You need special LEDs

Excellent results can be achieved with COTS LED devices, however high data rates are achievable using custom designed LEDs


Li-Fi Technology key players



Li-1st



Li-1st



Li-Flame

Ceiling Unit Desktop Unit



Li-Flame

-Multiple Users per AP-Halfduplex at 10Mbps



LiFi-X

Access Point Station



LiFi-XAccess Point Features:

Support for Power over Ethernet (PoE) or Power Line Communications (PLC)

Simple installation

Connect to a wide range of LED light fixture to form an atto-cell

Multiple access

Handover control enables seamless switching between APs



LiFi-XStation Features:

USB 2.0 powered

Supports handover, allowing user to move maintain their wireless session



Solar charging and connectivity at the same time



A high efficiency dimmable LED driver combined to an Indoor Positioning System



A high efficiency dimmable LED driver with a bi-directional Li-Fi communicationNot Available For Sale Right Now













Beamcaster Solutions

Point to Multipoint

Point to Point



Point to Point Network Features:

Uses Laser

Up to 10Gbps bidirectional connectivity

Up to 40m indoor range

Requires LOS



Point to Multi-Point Network Features:

Up to 1Gbps per user

Bidirectional connectivity

Requires LOS


Advantages and Limitations

Adva

ntag

esProvides High Bandwidth

Cost efficient

Safe for health

Very Secure

Does not suffer from fading

Can be used in RF restricted areas


Advantages and Limitations

Lim

itatio

nsLights must be always ON

LOS is usually needed

Bidirectional connectivity is complex

Limited to a small area

External sources can interfere


Comparison of Wi-Fi and Li-Fi

Parameter Wi-Fi Li-FiSpeed High Very High

Range Medium Low

Data Density Low High

Security Low High

Reliability Medium Medium

Transmit/Receive Power Medium High

Ecological Impact Medium Low

Obstacle Interference Low High

Market Maturity High Low


Li-Fi Energy Efficiency

Li-Fi is more energy efficient than Wi-Fi when the number of users is increased


Conclusion

Li-Fi takes benefit of visual spectrum to provide high-throughput data connectivity

High data rate and security are the main advantages

There are no health concerns about Li-Fi as it is with Wi-Fi

Li-Fi does not replace Wi-Fi, it is complementary to other wireless technologies

It is still under development and there are very few commercial products available


Any questions?


Thanks for your attention


Monenco Iran is a consulting engineering company formed in 1973 as a joint venture between the private sector of Iran and Montreal Engineering Company of Canada. In 1999, Mapna, AMEC, and Mir Company became the main share holders of Monenco.

Currently, Monenco plays the main role in Iran power industry and provides engineering, consultancy and supervision services in a broad range of target markets worldwide including; Combined Cycle and Thermal Power Plants, Renewable and Cogeneration, Distributed Generation, Electrical Power Transmission Lines, High Voltage Substations, Telecommunication, SCADA and Dispatching Centers, Electrical Railways, Electrical Network Studies, System and Energy Studies, Oil & Gas and Mining, Architecture, Civil, Urban Design and Roads.

Telecommunications department at Monenco Iran is active in different areas including RF solutions, IP networks and Fiber Optic infrastructures. We believe that spreading knowledge about emerging technologies is the first step towards their utilization.

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